Polymerization of ethylenically unsaturated hydrocarbons

ABSTRACT

A PROCESS FOR THE POLYMERIZATION OF ETHYLENICALLY UNSATURATED HYDROCARBONS, COMPRISING THE CONTACTING OF SUCH HYDROCARBONS WITH A CATALYST FORMED BY MIXING ALUMINUM TRIHYDROCARBONS (WITH THE HYDROCARBONS BEING EITHER ALKYL OR ARYL RADICALS) WITH A HEAVY METAL COMPOUND (FOR EXAMPLE A SALT, A FRESHLY PRECIPITATED OXIDE OR AN HYDROXIDE) OF THE METALS OF GROUPS IV-B, V-B AND VI-B OF THE PERIOD SYSTEM, INCLUDING THORIUM AND URANIUM.

' y 3 1974 K.ZIEGLER EFAL 3,826,792

POLYMERIZATION OF ETHYLENICALLY UNSATURATED HYDROCARBONS Original FiledNov. 15, 1954 5 Sheets- Sheet I H U. 9 8 7 6 5 L 3 I 0 9 klmmcsQQQDUMQOZ Fig.3

6 7 MOLECULAR RAT/O: AL /"7'/ IN VENTORS HEM/Z 44149727 BY W Army/M71Fig.4

MRI. Z/[GLE/f /////z BRE/L, ERHA R0 l/oLz/mM MOLECULAR RAT/O AL /7'/ y1974 K. ZIEGLER ETAL 3,826,792

POLYMERIZATION 0F ETHYLENICALLY UNSATURATED HYDROCARQONS Original FiledNov. 15, 1954 3 Sheets-Sheet s f? 350 9 k 300 5 el 250 S: g 200 5 l u 2I50 I I00 o 2 a z. 5 s 7 a MOLECULAR PAT/O AL/T/ aoo Fig.6 700 Q 9 LI200 X s I00 0|23456789|0l|l2|3l4 MOLECULAR PAT/O AL/HAVY METAL INVENTORSUnited States Patent 3,826,792 POLYMERIZATION 0F ETHYLENICALLYUNSATURATED HYDROCARBONS Karl Ziegler, 1 Kaiser-Wilhelm-Platz, HeinzBreil, Erhard Holzkamp, and Heinz Martin, all of Mulheim (Ruhr),Germany; said Breil, Holzkamp and Martin assignors to said Ziegler,Maria Ziegler sole heir of said Karl Ziegler, deceased Continuation ofabandoned application Ser. No. 745,998, July 1, 1958, which is acontinuation of applications Ser. No. 469,059, Nov. 15, 1954, now PatentNo. 3,257,332, Ser. No. 527,413, Aug. 9, 1955, and Ser. No. 554,631,Dec. 22, 1955, both now abandoned and Ser. No. 514,068, June 8, 1955.This application Mar. 17, 1971, Ser. No. 125,151 Claims priority,application Germany, Nov. 17, 1953, Z 3,799; Dec. 15, 1953, Z 3,862;Dec. 23, 1953, Z 3,882; Aug. 3, 1954, Z 4,348; Aug. 16, 1954, Z 4,375;Dec. 27, 1954, Z 4,629 The portion of the term of the patent subsequentto June 21, 1983, has been disclaimed Int. Cl. C08f 1/42, 3/06, 15/04US. Cl. 26094.9 B 32 Claims ABSTRACT OF THE DISCLOSURE A process for thepolymerization of ethylenically unsaturated hydrocarbons, comprising thecontacting of such hydrocarbons with a catalyst formed by mixingaluminum trihydrocarbons (with the hydrocarbons being either alkyl oraryl radicals) with a heavy metal compound (for example a salt, afreshly precipitated oxide or an hydroxide) of the metals of GroupsIV-B, V--B and VI-B of the Periodic System, including thorium anduranium.

This application is a continuation of application Ser. No. 745,998,filed July 1, 1958 now abandoned, which in turn, is a continuation ofapplications Ser. No. 469,059, filed Nov. 15, 1954, now US. Pat.3,257,332, Ser. No. 527,413, filed Aug. 9, 1955, now abandoned, Ser. No.554,631, filed Dec. 22, 1955, now abandoned and Ser. No. 514,068, filedJune 8, 1955.

This invention relates to new and useful improvements in thepolymerization of ethylenically unsaturated hydrocarbons for theproduction of high molecular polymers.

The polymerization of ethylene for the production of polymers rangingfrom gaseous through solid polymers is well known. When producing solidpolymers from gaseous ethylene, high pressures of, for example 1,000atmospheres and more, were generally required and oxygen or peroxideswere generally used as the polymerization catalyst. The yield obtainedby these conventional methods was generally low with, for example, about1520% of the ethylene being converted in a single operation into thepolyethylene. I

The highest polyethylene polymer which could be effectively obtained bythe prior known methods had a molecular weight of about 50,000.

It has also been proposed to polymerize ethylenes using aluminumtrialkyls as the polymerization catalyst. This polymerization reaction,however, is generally intended for producing low molecular polymers notranging substantially above the liquid range. It has further beenproposed to modify the polymerization using the aluminum trialkylcatalysts by the addition of auxiliary catalysts such as nickel orcobalt. In this connection, there are obtained molecular polymerizationproducts such as butene-l.

Higher molecular polyethylenes may also be obtained from ethylene usingan aluminum trialkyl catalyst by selecting a suitable quantity ratio ofthe aluminum trialkyl to the ethylene. It is, however, very diflicultto. obtain polyethylene of a molecular weight higher than a few thousandand it is necessary to use a very small quantity of the aluminumtrialkyl as, for example, aluminum triethyl for the production of highermolecular products. With the use of such small quantities of thealuminum trialkyl, however, the reaction becomes very sensitive totraces of impurity in the ethylene and proceeds very slowly, since thequantity of catalyst in the total reaction mixture is very small.

One object of the invention is a new process for polymerizingethylenically unsaturated hydrocarbons.

Another object of this invention is a new process for polymerizingethylene into high molecular polyethylenes which may be used asplastics.

A further object of this invention is a new process for thepolymerization of ethylene into high molecular polyethylenes with ahigher yield than heretofore obtainable.

A still further object of the invention is the polymerization ofethylene into polyethylenes having molecular weights higher than thoseheretofore obtainable.

A still further object of the invention is a novel high molecularpolyethylene.

These and still further objects will become apparent from the followingdescription:

In accordance with the invention at least one ethylenically unsaturatedhydrocarbon of the general formula CH =CHR is polymerized into highmolecular products by contact with a catalyst formed by mixing at leastone Al-trihydrocarbon i.e., Al-alkyls, -aryls and mixed-alkylaryl, andpreferably at least one member of the group consisting of Al-trialkyls,Al-triaryls, Al-triaralkyls, Altrialkylaryls and Al-trihydrocarbonshaving mixed alkyl, aryl aralkyl and alkylaryl substituents with acompound of a heavy metal of Group IV-B, V-B or VI-B of the PeriodicSystem of elements, including thorium and uranium, said compound beingselected from the group consisting of the salts, and the freshlyprecipitated oxides and hydroxides of said metals. R in said formula maybe hydrogen or a hydrocarbon radical.

The designation Al-aryl or similar expression as used herein genericallyis intended to include as is well understood in the art an organicAl-compound having one or more aryl, aralkyl or alkylaryl substituents.

Except as otherwise limited herein, the term "salt or salts" designatinga compound having a heavy metal of the IV-B, V-B and VI-B groups of thePeriodic System, including thorium and uranium, is employed in itsbroadest sense, i.e. to connote the reaction product between a base andan acid, including products of the type of acetylacetonates and furtherincluding salts in which said Periodic System group member is present asa cation as as those in which such member is present as an anion such inproducts of the type of titanates, zirconates, chromates, inolybdates ortungstates. The term pure alcoholates hereafter used in designation ofthe said salts" is intended to connot salts having solely alcoholateradicals attached to said heavy metal. Mixed alcoholates of said heavymetals as hereafter referred to are such salts having at least onealcoholate radical and at least one nonalcoholate radical.

Particularly good results are produced with heavy metal compounds whichare soluble in inert organic solvents such as hydrocarbons.

The term high molecular as used herein is intended to designatemolecular weights of more than 2,000, and preferably more than 10,000.

The herein designated numerical values for molecular weights are based,in accordance with conventional practice, on the viscosity of thesolutions of the polyethylene for which the molecular weightdetermination is to be made. This viscosity is expressed] as intrinsicviscosity which is to be calculated on the basis of an equation given bySchulz and Blaschke (Journal fiif Praktische mono-,

Chemie, Volume 158 (1941), pp. 130-.-135,equation 5b,

p. 132) and corrected for the therein mentioned specific viscostiyaccording to Fox (Fox and Flory, J. Soc., 73 (1951') p. 1901).-Theaverage molecular. weight, as

for instance that of 50,000 above given, is calculated from suchintrinsic viscosity by way of the modified equation of R. Houwink(Journal fiir Praktische Chemie, new Edition 157 (1940), pp. 15-16,equation 5):

for which the constant K=2.51 10 and the constant a=1.235 for the newplastics is intended. n the basis of molecular weights calculated inthis manner, polyethyl-.

enes having molecular weight of 300,000 up to 3,000,000 and more may beobtained in accordance with the invention.

In general the Al-tri-hydrocarbon is preferably one in which thesubstitutents possesses from 0 to one and more aromatic hydrocarbonrings of from C to C i.e. the benzene and naphthalene rings.

The aluminum trialkyl compounds which may be used in forming thecatalysts in accordance with the invention may be any conventional orknown aluminum trialkyl as, for example, aluminum trimethyl, aluminumtriethyl, aluminum tripropyl, aluminum triisobutyl, or higher aluminumtrialkyls (especially in excess of C Convenient higher Al-trialkyls arefor instance those within the range of average composition of about C toC such as an average composition of aluminum trioctyl or tridodecyl ortheir mixtures. The higher trialkyls are without limitation to thenumber of carbon atoms. Examples of Al-aryls which may be employed are:aluminum triphenyl, -tritolyl, -trixylyl and -trinapthyl and includesuch aralkyls (the A1 is linked to the aliphatic chain) as aluminumbenzyl or aluminum phenyl ethyl. Mixed Al-alkyls and -aryls useful inaccordance with the invention are compounds in which the Al is linkedboth to alkyl residues, for example methyl or ethyl, and also to arylresidues or aralkyl residues, for example phenyl or 'benzyl.

The compounds of the metals which are mixed with the aluminumtri-hydrocarbon to form the catalyst may be any compound of a metal onthe left-hand side of the IVth to VIth Groups of the Periodic System,including thorium and uranium. In certain of the newer Periodic Chartsof the Elements, these metals on the left-hand side of the IVth to theVIth Groups of the Periodic System are, designated as Groups IV-B, V-Band VI-B respectively. The term heavy metal is used herein in contrastwith the relatively lighter metal aluminum. When reference is madeherein and in the claims to metals of Groups IV- E, V-B and VI-B of thePeriodic System, there is intended any member of these groups, includingthorium and uranium, as for example, titanium, zirconium, hafnium,thorium, uranium, vanadium, niobium (columbium), tantalum, chromium,molybdenum and tungsten. Any compounds of these metals such as thehalogenides, for example chlorides or bromides, oxyhalogenides, forexample oxychlorides, complex halogenides, forexample, comple fluorides,freshly precipitated oxides or hydroxides or organic compounds, forexample pure alcoholates of the type of esters such as titanium-,zirconiumetc. tetrabutyl esters, mixed alcoholates, acetates, benzoatesor acetyl acetonates and similar compounds may be used. Also mixedcompounds, as for example of the type of dior tri halogeno (preferablychloro-) alcoholates of said heavy metals may be used. Salts oftitanium, zirconium, uranium, thorium and chromium have been found to bepreferable.

A particularly active catalyst in accordance with the invention may beobtained, for example, by mixing a titanium or zirconium compound, suchas a tetrachloride, oxychloride or acetyl acetonate with the aluminumtrihydrocarbon.

The exact nature of the catalyst produced by mixing of 4 the metalcompound of Groups. IVB,.to..VITB.and .the aluminum tri-hydrocarbon visnot known.

The heavy metal compound is converted to a lower valency form. Thus, forexample, upon bringing together the tetravalent zirconium compound andthe aluminum trialkyl, there is formed a compound 'of monovalent,bivalent or trivalent zirconium. The fact' that the quadrivalentzirconium salt undergoes a conversionjmay be clearly noted from thefact" that'the initiallycolorless salt dissolves in the aluminumtrialkyl, becoming darker in color and generating heat. Whilethe'special polymerizing action of the catalyst in accordance with theinvention may come from the combination with the aluminumtri-hydrocarbon, probably the low valence group IV-B, VB, or VI-B metalcompound has 'a high polymerization effect by itself, since for examplethe action of the Al-trialkyl derived catalyst on ethylene, starts at" alower temperature and takes place more rapidlythan the normal reactionof aluminum trialkyl with ethylene.

Within the broadest concept of the invention the ratio ofAl-tri-hydrocarbon to-heavy metal compound is not critical with respect:to' the obtaining per se gof high molecular polymers such as exemplifiedbypolyethylenes with molecular weights from 10,000, to 3,600,000 ,andhigher. Expressed in mol ratios they may run from fractions, as forexample 0.1, or even less, to multiples of 1, such as 12 or higher, ofAl-tri-hydrocarbon/heavy metal compound. In the event that the heavymetal compound is a true alcoholate, it is preferable to utilize-a molratio of Al-tri-hydrocar-bon/heavy metal compound of at least about 1021since such alcoholates will also produce dimers and the dimerization isincreasingly favored with decreasing mol ratios. v

Whenever the primary objective is to' assure that particularly highmolecular weights aresecured for the polymer produced by use of thecatalyst in" accordance with the invention, or, when oxidizingimpurities, as for example moisture or oxygen, are present, such as inethylene, or in any solvent, it is preferred to utilize an excess ofAl-tri-hydrocarbon. In that case it is of advantage to use at least 2mols of the Al-tri-hydrocarbon for each mol of heavy metal compoundregardless of its valence and preferably, in the case of heavy metalcompounds other than acetyl acetonates, 2n to 3n mols of the aluminumcompound to every mol of the heavy metal compound n being the valence ofthe heavy metal.

A typical illustration of such mol ratios is for instance a combinationcomposed of one mol of a tetravalent'titanium salt such as TiCl, and 8-12 mols of Al-trialkyl. The reasons for the desirability, of an excessof Al-cojmpound, in the event of for example the presence .ofoxidizingimpurities, are based on the following considerations:

When the aluminum tri-hydrocarbon acts for instance on the tetravalenttitanium salt, a reduction takes place which, however, does notreduce'the titanium to metallic titanium. If the aluminumtri-hydrocarbon. reacts at first only with one of its hydrocarbonradicals such as an alkyl, as for instance an ethyl group as is true ingeneral for the reactivity of these organic aluminum compounds, not morethan three molecules of aluminum tri-hydrocarbon will presumably beconsumed in the reduction of the tetravalent titanium salt. An excess ofhydrocarbon radical component beyond that serving for preparing thecatalytically effective material is then normally present when using theabove referred to multiple mol amounts specified for heavy metalcompound combinations other than acetylacetonates. The excess ofaluminum trihydrocarbons is of value to counteract the oxidizing actionof impurities frequently present when utilizing the catalyst.

The minimum quantities of the catalysts in relation to monomer, forexample olefine such as ethylene, may vary within very wide limits andare dependent upon the purity ofthe material to be polymerized. Whenusing for instance .very pure,ethylene, 0.1 parts of catalyst to 1,000parts of ethylene will already be suflicient. It is evident that largerquantities can be used even in the case of pure -.-ethylene. However, itis desirable to avoid using unnecessarily large quantities of catalystso as not to make the working up process more difficult than isnecessary. Taking very impure monomer, such as ethylene, good resultscannevertheless be obtained with quantities of catalysts amounting toonly a few percent. If solvents are used for the polymerization, thesame applies in connection with the purity of the solvent. Thequantities of catalysts employed influence the molecular weight of thepolymers produced so that the degree of polymerization and thus themolecular weight will be higher the small the quantity of catalystsemployed. On the other hand the higher the catalyst concentration thelower will be the molecular weight.

1 The influencing of the molecular weight however, by

altering the concentration of the catalyst, has its limitations, in thatan increase in the catalyst concentration leads to an increasedconsumption of catalyst and this makes the process more expensive. Inaddition, the polymers. obtained with high catalyst concentrationscontain more ash than those made with low catalyst concentrations andmust have this ash removed therefrom by complicated lixiviation orwashing with solvents. On the other hand, when the catalystconcentration is considerably reduced for the purpose of raising themolecular weight, the reaction velocity of the polymerization isappreciably reduced and consequently also the yield per unit of volumeand time. Moreover, the control of molecular weight by variation ofcatalyst concentration cannot readily be applied to the range ofmolecular weights below 100,000,

, which is a particularly important range in practice.

Within the scope of one embodiment of the instant invention it ispossible to obtain for the polymers, variations in molecular weight in amanner avoiding or at least appreciably minimizing some or all of thedisadvantages entailed by variation in catalyst concentration and tosecure benefits not obtainable by the latter method. This embodiment isbased on the discovery that for catalyst combinations, usable inaccordance with the invention, variations in mol ratios ofAl-tri-hydrocarbons/heavy metal compound will produce differentmolecular weight polymers. Broadly speaking, lower mol ratios will yieldlower molecular weight products and higher mol ratios will give highermolecular weight products. It is thus I possible for any given catalystcombination to obtain polymers of predetermined molecular weights byselecting specific predetermined mol ratios for that combination.

The mol ratio variation effect is in each case readily ascertainablefrom the curve or graph obtained when plotting different mol ratios ofgiven catalyst combinations, useful in accordance with the invention,against the respective molecular weights of the polymers obtained by theuse of these given combinations. Such curves or graphs are for instanceillustrated in the accompanying drawings by way of FIGS. 1-6. They showthe easy securability of any desired molecular weight by selecting theappropriate mol ratio.

It has been further found that each Al-tri-hydrocar- .bons/heavy metalcompound mol ratio versus molecular As will be seen in accordance withthe foregoing and the more specific exemplification by the illustratedgraphs hereafter more fully discussed, the steep portion of the molratio versus molecular weight curve defines for relatively smallincrements in mol ratio relatively large increments in molecular weight.

The curve portions adjacent the steep portion, i.e. those immediatelyfollowing and those immediately preceding the above identified steepportion of the graph, defining mol ratio versus molecular weight, inaccordance with the invention, may also show for relatively smallchanges in mol ratio relatively large variations in molecular weight.Whereas the steep curve portions normally show molecular weightincreases with rising mol ratios of catalyst, the adjacent curveportions, may comprise a portion or may be composed of sections in whichincrements in mol ratios produce decreases in molecular weights. Thoughthe preceding curve portion may exhibit a lesser change in molecularweight than is the case for the curve portion succeeding the steepportion, the former may offer nevertheless appreciable advantages. Thus,such, preceding curve portion within the range of molecular weights,controlled thereby permits the selection of mol ratios requiring acomparatively small amount of the relatively expensive, and in higherconcentration more difiicult to handle aluminum tri-hydrocarbon. Withinthe preferred scope of this embodiment of the invention there areincluded the steep portion of the mol ratio versus molecular weightcurve as well as its adjacent lower and upper curve portions showing forrelatively small changes in mol ratios relatively large changes inmolecular weight. This preferred range is designated in accordance withthe invention as the sensitive range. If the primary consideration is toaccomplish savings in aluminum tri-hydrocarbon material it is ofadvantage to select that portion, and preferably initial portion, of themol ratio versus molecular weight curve which in the direction ofincreasing mol ratios: ends (as part thereof) with the relatively steep(inclining) portion thereof. Because of the obvious advantages, however,offered by the steeply pitched portion of the curve or graph, the preferred range of the mol ratio versus molecular weight curve is normallyrepresented by the steep portion thereof as hereinabove defined.

Inasmuch as increasing mol ratios mean relative decrease in heavy metalcompounds: which may be in some cases more expensive than some of themore readily available aluminum-tri-hydrocarbons, the sensitive rangealso permits the determination for selection of a desired molecularweight with the least amount of heavy metal compounds. Further thesensitive range permits in all cases the determination of the highestmolecular weight at the most economical mol ratio of materials. Aboveall, however, the sensitive range and especially the steep curve portionthereof permits the obtaining of any desired predetermined molecularweight furnishing therefor predeterminately fixed ratio of catalystcomponents within a relatively narrow range of adjustment to cover avery wide and in many cases, the entire molecular weight rangeobtainable for a particular catalyst and condition of polymerization.

An exemplification of the sensitive range of differential mol ratios fora specific catalyst. combination is for instance furnished by Table Iand curve A (FIG. 1). The combination is that of Ai(C H17);3 and TiCL,and Table I sets out by way of exemplification the results of a num berof ethylene polymerization experiments with the aluminum trioctyl andtitanium tetrachloride system using different mol ratios. Theseexperiments and the experiments represented by the other Tables werecarried out as follows:

The amount of aluminum tri-hydrocarbon necessary for each experiment wasinitially dissolved in 250 cc. of diesel oil distilled with sodium andhaving a boiling point of l-240 C., the said oil being produced bycarbon monoxide hydrogenation according to Fischer-Tropsch.

7 In allbasesthe same amount of heavy metal compound, such as fortitanium tetrachloride-4.75 g. thereofjw'er'e then added dropwise atroom temperature whilestir'ring. In' addition, 2.25 liters of the saiddiesel oil were saturated with ethylene in a closed stired typeapparatus filled with nitrogen and then the catayst "solution" wascaused to runin. If the heavy metal compound doesnot readily lend itselfto dropwise addition, or where 1t 18 otherwise desirable, the same maybe added in an organic compound per mol of titanium tetrachloride (TableI) and (FIG. 1) and then reducing in stages the amount of organicaluminum compound used while keeping the amount of titaniumtetrachloride constant, the influence of this step on the molecularweight of the polymers is 2 initially slight (section a, curve A). Onlya relatively weight o'f the polymer c'hanges' considerably with'a'relati'v'ely -srnall' change i molecular 'ratio are 02:1 and 3: 1 andpreferably 2: 1. Any section of 'c'urve A defined by the curve-portionbetween".2 and 2.0 mol ratios, includingthat between 0.2 and 0.5,corresponds to a greater molecular weight 'change'per- 0.3 mol ratiosthan any section following2EO. The limits ar'e diiferent withothe'r'combinations. a i

The essential feature'of this sensitive range embodi- 0 ment of thepresent invention does not consist so much in determining theaccurate-numerical limits of these sensitive ranges or the preferredsteep portion thereof for each conceivable combination, as in thefundamental discovery that there isin fact such'a sensitive range or asteep portion. The position or scope of thisrangecan be determinedeasily for any given combination by a small series of experiments andplotting the results of the experiments by means of curves. The valuesgiven in Table I and the other tables are those selected from a 0 largernumber of intermediate values and define the section terminal of thecorresponding curves.

TABLE I Yield after Molecular 4 hours of H Average ratio, reactionmolecular Number of Al(CaH 11)3: g. of poly- (1 weight of Meltexperiment T1014 ethylene dl./g. polymer index brown. Reddish- 440 7. 15284, 000

brown. I

slight increase in the average molecular weight of the polyethyleneoccurs up to a ratio of about 3:1. Thence to a ratio of 2:1, themolecular weight again increases somewhat more strongly to the region of320,000 under the conditions set above (section b, curve A). A steeprange then follows (section e, curve A) in which extraordinarily smallchanges in the ratios exert quite an appreciable influence on themolecular weight of the polymers obtained. If a ratio of 2Alz1Ti isinitially used and if the ratio is changed to 1:1 to 05:1, this causes adrop in the molecular weight from 320,000 to 20,000, so that it ispossible to obtain any desired molecular weight between about 20,000 and320,000 by a fine adjustment of the ratio between the organic aluminumcompound and the titanium tetrachloride within this range 0 of curve A.

The figures indicated in Table I only apply for the experimentalconditions which have been set forth, since there are, as alreadymentioned, other factors which infiuence the molecular weight of thepolymer. Depending on these other conditions, the polymerization curvesmay plot differently and the starting point of the steep ranges may beshifted to different levels. This is particularly pronounced when usinga high molecular ratio between an aluminum trialkyl and titaniumtetrachloride.

.For any given set of polymerization conditions and catalystcombination, however, if the molecular ratio of aluminum trihydrocarbonto heavy metal compound is reduced, a range such as the sensitive rangeb-i-c-i-d of curve A exists in which further changes in molecular ratiopermit an extraordinarily sensitive regulation within a relatively widerange of any desired predetermined molecular weight of the polymer. Thisis particularly true of range a. In certain cases the entire sensitiverange may be essentially composed of the steep portion of the curve suchas section c of curve A.

As will be seen from Table I and curve -A (FIG. 1),

the limits of the sensitive range in which the molecular For molecularratio values higher than the top of the steep portion of thesensitiverange, as exemplified on curve A by the 2:1 ratio, the molecular weightof-the polymer is not appreciably altered. If the molecular ratio valuesare lower than the starting point. of the sensitive ranges, i.e., oncurve A beyond 0.221, this also has no great influence on the molecularweight of the polymer which is formed. However, the volume-time yield isconsiderably reduced and soon a zone is reached in which it is no longerpossible for the polymer to be produced economically with lowpolymerization pressures. This can to a large extent be counteracted byraising the polymerization pressure. However, particular technical advantages do not result from such aprocess.

Polymerization with the catalysts in accordance with the broad andgeneric. scope of invention is effected by merely contacting thematerial to be polymerized with the above described catalyst. This maybe carried out under reaction conditions generally considered andconventionally termed in the art as mild reaction condition (as totemperature and pressure). The contacting may be effected at normal orup to about 10 atmospheres pressure or at comparatively low pressures ofabout 10-100 atmospheres; the contacting pressure is not critical and asmooth polymerization may be effected at atmospheric or sub-atmosphericpressures. On the other hand, the action of the new catalyst remainsfundamen tally unchanged, even if the pressure is increased to anydesired obtainable value. It is advantageous to work at pressures of 1to 10 atmospheres. It is an outstanding advantage of the invention thatone may operate at ordinary atmospheric pressure with excellent results.

The monomer may be added in vapor phase which is of particular advantagewhen usingnormally gaseous olefins such as ethylene.

Previously known high pressure ethylene polymerization processes havethe further disadvantage that ordinarily only a relatively smallproportion of approximately to of the ethylene introduced is convertedinto polyethylene. On the other hand, ethylene treated with a catalystin accordance with the. invention is predominantly converted. Moreover,the ethylene to be employed with the catalyst of the invention need notbe so pure as in the known high pressure processes.

The temperature of the contacting is not critical and the same may beeffected at room temperature or below. It is advantageous to operate atsomewhat elevated temperatures and particularly above about 50 C. Thusin olefine polymerization, as contrasted to prior art processes, themonomer contacted with a catalyst in accordance with the invention maybe rapidly converted into high molecular polymer even at low pressuresof less than 100 atmospheres and temperatures of less than 100 C.Working at temperatures above 250 C. is not advisable because at thistemperature the catalysts may decompose to a considerable extent.

In the practical application of the invention it is also possible tocontact the novel catalyst material with several ethylenicallyunsaturated hydrocarbons to thereby obtain copolymerization. Thus, amixture of olefins such as an ethylene containing gas mixture may bedirectly used for the polymerization, for example, gases'which aregenerated during the cracking of saturated hydrocarbons, such as ethaneor propane, or from mineral oil or its fractions, or generated duringsimilarly conducted Fischer-Tropsch synthesis; if desired, they may befreed from other olefins than those desired for the polymerization.

The activity of the catalyst and the degree of polymerization of thefinal substances obtained are dependent upon the metal compoundsselected, the manner of its preparation and the ratio of the quantity ofthe heavy metal compound to the quantity of the aluminum trihydrocarbon,the latter determining largely the degree of polymerization as above setforth.

Thus, it has been found that, when using suliicient quantities of theGroups IV-B to VI-B metal-containing components of the catalyst,titanium-containing catalysts are more active than zirconium-containingcatalysts. The activity of the catalyst can be further substantiallyincreased by using for the preparation, instead of a relatively lowmolecular aluminium tri-hydrocarbon one having larger hydrocarbonradicals. This is particularly true for Al-tri-alkyls from which higheralkyls may be advantageously obtained, for example, from aluminumtriethyl by combination with ethylene. It is in many cases preferred tooperate in the presence of solvents. Suitable solvents are: aliphaticand hydroaromatic hydrocarbons, such as pentane, hexane, cyclohexane,tetrahydronaphthalene, decahydro-naphthalene; higher paraffins, also inmixtures; paraffins liquid at the reaction temperature; aromatichydrocarbons, such as benzol, xylol, halogenated aromatic hydrocarbons,such as o-dichloro-benzol, chlorinated naphthalene; ethers such asdibutyl-ether, dioxane, tetrahydrofurane. These solvents are used insuch quantities that it is still possible to stir the reaction mixtureeven when it is nearing the end of the reaction. Generally this stirringoperation is possible even when the reaction mixture, as in the case ofethylene, contains 10 to 40% polyethylene at the end of the reaction.Maximum limits only exist as regards the economy of the process.

The preparation of one form of catalysts, useable in accordance with theinvention, by the use of solutions of at least one component, such asthe Al-trihydrocarbon is for instance exemplified when titaniumtetrachloride is introduced, drop by drop, into a hexane solution ofaluminum triethyl such as in a molar ratio of 1:8, the solution assumesa dark color and a difiicultly soluble black precipitate deposits, whichcontains aluminum and titanium. This diflicultly soluble compound, theexact structure of which is not known, is believed to be the truepolymerization exciter. With suspension of this precipitate in a solventsuch as hexane, ethylene can be readily polymerized, even at normalpressure. The hexane assumes a deep color and contains the same compoundapparently in a colloidally dispersed state. The amount of precipitatewhich remains colloidally suspended and the amount which separates outvary with the manner in which the precipitate is formed. The colloidallydispersed form is, in some cases, more reactive, in any event, however,it can be more conveniently dosaged than they difficultly solubleprecipitate.

The formation of catalyst precipitates can be minimized or substantiallyovercome so as to yield primarilyxin the first instance substantiallycolloidally dispersed solutions it higher molecular Al-trihydrocarbonsand preferably Al-alkyls are used. Thus if, instead of using a solutionof aluminum triethyl in hexane, there is used a solution of a higheraluminum trialkyl which, for example, has approximately the averagecomposition of an aluminum trioctyl, there is obtained a completelyhomogenous dark solution of the polymerization catalyst.

Polyethylenes obtained by use of the catalyst in accordance with theinvention, as has been set forth above, have an extremely high molecularweight which may range up to 3,000,000 and more. These polyethylenes arebelieved to be completely novel and different from the solidpolyethylene polymers previously obtained. These new polyethylenes havea softening point or melting point, which will be generically referredto herein as the softening point, of more than 130 C. and are insolublein all solvents at room temperature.

The polyethylenes produced in accordance with the invention, having amolecular weight up to about 100,000 will in most solvents onlypartially dissolve at a temperature above about 70 C., While thosehaving a molecular weight above 100,000 will only partially dissolve insuch solvents at temperatures above about 100 C. The temperaturestability or resistance of the new polyethylenes is greater than that ofthe known conventional polyethylenes. Upon heating the new products totemperatures above 250 C. they retain their white color, while the colorof the known products changes to gray between 200 and 250 C. Theresistance of the new polyethylenes to oxidation by atmospheric oxygenis also much greater.

The new polyethylenes in accordance with the invention have a highcrystal content which is unusual for high molecular hydrocarbons. Thedegree of crystallization, as shown by X-ray diagrams, generally amountsto and in many cases even higher. At times also lower values may occur.The crystallinity remains unchanged to a temperature of C. or higher anddisappears only near the softening point.

The new polyethylenes are almost completely linear in molecularstructure and have practically no branch chains. In general, thepercentage of the methyl groups is relatively small, being at most about0.03% and in some cases even less than 0.01%. Infra-red spectrographs ofthe new products in accordance with the invention do not show thecharacteristic methyl band of the prior known polyethylenes.

The tear strength of the new polyethylenes in accordance with theinvention is a minimum of about 100 kilo grams per square centimeter,and frequently more than about 200 kilograms per square centimeter. Thetensile strength in undrawn condition is more than about 200 kilogramsper square centimeter and in elongation-oriented films or sheets, up toabout 3,000 kilograms per square centimeter. 5

The products may be worked directly, for example, between heated plates,into clear, transparent, elastic and flexible plates or sheets. Thepolyethylenes are also well suited for working in extrusion presses orfor injection molding. In molten state they can be spun into threads bythe methods usually employed for spinning superpolyamide threads. Theymay be cold drawn and may be drawn in this manner into ribbons, wires,or filaments of high elasticity and strength such as have never beenobtained with prior known polyethylenes. Already in the working, the newpolyethylenes show a remarkable tendency toward fiber formation. Thethreads produced from the new polyethylenes can be used as threads forindustrial purposes. The new products can be spun to form filaments inthe molten state by the methods which are conventional for the spinningof superpolyamide fibers such as nylon fibers. The filaments producedfrom the new polyethylenes can be employed as fibers for industrialpurposes.

In copolymers produced according to the invention, either thealpha-olefine or the other monomer or monomers may predominate in thecopolymer molecule. Thus, we have produced copolymers of propylene andethylene containing, by weight in the polymer molecule, of propylene and90% of ethylene. We have also produced copolymers containing, in thepolymer molecule, 30% of isobutylene and 70% of ethylene. Copolymerscontaining, in the polymer molecule, 50% of pro pylene and 50% ofethylene have been prepared by the method described herein. Copolymerscontaining up to 70% ethylene and up to 30% propylene are contemplated.

The following examples are given by way of illustration and notlimitation, all operations involving the handling or obtaining ofnormally pyrophorous materials or of those tending to be pyrophorous andespecially the catalyst combinations being carried out in an inertatmosphere such as N as is conventional practice in the art.

EXAMPLE 1 20 cc. of aluminumtripropyl are carefully mixed with 0.2 gramstitanium tetrachloride, which results in a very vigorous generation ofheat. The solution becomes an opaque black, and is introduced undernitrogen into an autoclave of a volume of 500 cc. 60-70 grams ofethylene are forced into the autoclave which is then heated whileshaking to 100 C. Within the course of 15 hours, the pressure drops toabout atm. The reaction mixture is allowed to cool and the excessethylene is blown off. The content of the autoclave is in the form of apaste-like mass which consists of a mixture of high-molecular ethyleneand low-molecular liquid and solid, soluble products. It is stirred withmethyl alcohol, extracted with methyl-alcoholic hydrochloric acid andthereupon with acetone. There remains 30 grams of an insoluble residueof high melting point which consists of a snow-white, finely granular,powdered mass of polyethylene. The powdery mass is pressed between metalplates heated to 150 C. and thereafter rapidly cooled, thus, forming afilm which is extremely elastic and can be torn only with theapplication of a very great force.

EXAMPLE 2 2 grams of titanium tetrachloride were added, drop by drop,with the exclusion of air, into 40 cc. of aluminum triethyl. A blackprecipitate formed with a vigorous pro duction of heat. 200 cc. ofhexane were added to the mixture, and a part of the dark substance whichhad formed precipitated and another portion remained in solution with adark color in the hexane, presumably in colloidal solution. The hexanefraction was transferred into a 500 cc. autoclave which was filled withnitrogen and ethylene was introduced up to a pressure of 60 atmospheres.Upon shaking, the temperature increased spontaneously to 60 C. and thepressure dropped atmospheres. The introduction of ethylene underpressure was repeated but another strong rise in temperature was notnoted. Nevertheless, the ethylene pressure receded again though moreslowly. Ethylene was introduced under pressure a total of five times, atotal of 88 grams of ethylene being introduced in this manner into theautoclave. After a total of 65 hours, it was possible to blow only 4grams of ethylene out of the autoclave. The content of the autoclaveconsisted of a solid mass which could be crushed only with difficultyand which had completely absorbed the solven'tused. This mass was browenout of the autoclave in a suitable manner, introduced into methylalcohol and thereupon heated with methyl-alcoholic hydrochloric acid.After filtration, washing with methyl alcohol and drying, grams of awhite diificultly soluble powder were obtained which was pressed betweenheated metal plates at 160l70 C. to form clear transparent sheets havingextremely good mechanical properties. A narrow strip cut outof such asheet was stretched in the cold to about 3-4 times its length, in whichconnection the characteristic phenomena known from the stretching ofpolyamide tapes was observed. The tear strength of the stretched tapeswas as high as 30 kg./mm.

EXAMPLE 3 Example 2 is repeated using as the polymerization 'excitor theblack precipitate which settled upon dilution with hexane which wascompletely freed from dissolved portions of aluminum triethyl byrepeated formation of a suspension with hexane, settling and pouring oifof the solvent all with the exclusion of air. In all other respects theprocedure and results are substantially the same as in Example 2.

EXAMPLE 4 500 cc. of liquid paraffin are deaerated by the introductionof nitrogen and heating to C. After cooling there are added 58 grams ofan aluminum trialkyl of the average composition of aluminum tridodecyl,whereupon 2.6 grams titanium tetrachloride are admixed while stirringunder nitrogen. The mixture becomes an opaque black. However, no solidprecipitate settles out. Thereupon ethylene is introduced while stirringat room temperature. The temperature rises during the course of /2 hourby itself from 23 to 43 C. and the ethylene is vigorously absorbed at arate of about 10 grams per hour. Soon after the beginning of theexperiment it can be noted that a difficultly soluble substanceseparates out of the mixture. After about 3-4 hours, the absorption ofethylene decreases. There is then added, while stirring, 200 cc. hexanein order to dilute the reaction mixture and make it more easilystirrable, whereupon methyl alcohol is added. The reaction mixture atfirst still remains dark. Only upon suction filtering in contact withair does it change into a light olive green. This color is furthermoreat first characteristic of the filtered precipitate. If the precipitate,after washing with methyl alcohol, is heated very slightly with about 5%nitric acid, it becomes pure white. It is then again filtered, washedwith methyl alcohol and dried. There are obtained 40 grams of a purewhite very loose powder which after pressing into sheets shows all theproperties described for the product obtained in accordance with FIG. 2.The activity of the catalyst can be improved and more polyethyleneobtained per gram of catalyst if the entire quantity of catalyst is notintroduced at the, beginning but the catalyst is rather added graduallydrop by drop over a lengthy period of time. The same test can also becarried out with cooling of the reaction mixture to 20 C., particularlyif a more readily mobile solvent such as hexane is used instead ofliquid paraffin. The reaction time is then of course increased.

EXAMPLE 5 Example 4 is repeated but the solution of the catalyst in theliquid paraifin is warmed to about 4050 C. and then the gas mixture ispassed through it. The said gas mixture contains about 10-20% ethyleneas obtained by the thermal cracking of ethane. The course of thereaction is substantially the same as Example 4 but it takes about l01.2 hours before the same quantity of polymer is formed.

13 EXAMPLE 6 6 liters of hexane, 82 grams aluminum triethyl and 24 gramstitanium tetrachloride are stirred with ethylene of a maximum pressureof atm. in the apparatus described in the preceding example. The initialtemperature is C. The temperature rises by itself to C. After a total of12 hours, the reaction is interrupted. There is then present in theautoclave a thick paste which is worked up in the manner described indetail in Example 5. There is obtained about 1 kg. of a colorless,high-grade polyethylene which can be used directly as molding powder.

EXAMPLE 7 1 gram of solid zirconium acetylacetonate is carefully addedto cc. aluminum triethyl. The zirconium salt passes into solution with ayellow color and the color then changes after it has been standing forabout 10 minutes via brown to black. 200 cc. of hexane are added to thismixture whereupon it is introduced, under nitrogen, in a 500 cc.autoclave of ordinary steel. A total of 110 grams ethylene is thenintroduced under pressure in about 4 portions. The addition of theethylene is so regulated that the initial pressure after the heating toabout 100 C. is 90-100 atm. The autoclave is then shaken at 100 C. Twoto three hours after the introduction of ethylene in each case there isnoticed a rapid decrease in the pressure down to l020 atm. After theintroduction under pressure of a total of 110 grams ethylene, theethylene absorption proceeds only slowly evidently due to the fact thatthe contents of the autoclave have solidified at this time into amixture of solid polyethylene and hexane which is no longer mobile andtherefore can no longer be brought actively enough into contact with theethylene by shaking. By using an autoclave which is provided with astrong agitator, this difficulty can be avoided and the absorption ofthe ethylene continued further. Small quantities (5 grams) ofnon-polymerized ethylene are thereupon drawn off and the autoclaveopened. The content consists of a solid, snow-white mass dispersed withliquid which is stirred with methyl alcohol, suction filtered, heatedwith methyl-alcoholic hydrochloric acid in order to remove the metalcompounds and then washed with methyl alcohol. No substantial quantitiesof soluble parafiin are extracted from the mass with boiling acetone.After drying at about 100 C. the polyethylene represents a snow-white,finely granular powdered mass which upon pressing between metal platesheated to 150 C. followed by rapid cooling is converted into a clear andsometimes opaque film. This film is extremely elastic and can be tornonly with the application of a very great force. The yield ispractically quantitative.

EXAMPLE 8 In a 14 liter autoclave provided with an agitator, there aremixed, under nitrogen, 6 liters of benzene, 88 grams aluminum triethyland 10 grams zirconium acetylacetonate. Thereupon heating is effected toC. and ethylene is introduced up to a pressure of about 5 atm. Thepressure is maintained at this level and stirring elfected for 10 hours.The mixture is then allowed to cool; the unreacted ethylene is blown offand the autoclave opened. A colorless polymer has precipitated in anextremely peculiar form on the agitator as well as on the bottom of theautoclave. The polymer consists of a mass of slightly swollen filamentswhich somewhat resemble long-fibered asbestos. The mass can be veryeasily removed from the agitator, washed with benzene and dried.

EXAMPLE 9 20 cc. of aluminum triethyl are mixed with 20 cc. hexane and 2grams thorium acetylacetonate are introduced into this mixture. Theacetylacetonate passes into solution and the mixture assumes a lightyellow color, and spontaneously heats up to near the boiling point ofthe hexane. At the same time gas is generated. The mixture isintroduced, under nitrogen, into a 500 cc. autoclave and 180 cc. ofdistilled, air-free hexane are added. Thereupon grams ethylene areintroduced under pressure and the autoclave heated to 95 C. The pressurerises temporarily to about atm. but starts to decrease again before theautoclave has reached the temperature of 95 C. The autoclave is shakenfor 40 hours at 95 .C.. and allowed to cool, whereupon any excesspressure which is still present is released. 3 grams of gaseousconstituents escape consisting principally of ethane which is normallyadmixed with the ethylene. The content of the autoclave consists of areadily stirrable paste of a snow-white fibrous polyethylene suspendedin hexane. The metal organic compounds are decomposed by the addition ofmethyl alcohol and suction filtered and the solid polyethylene is heatedwith methyl-alcoholic hydrochloric acid in order to eliminate the metalcompounds. After the filtering, washing with methyl alcohol, and dryingthere are obtained 102 grams of the polyethylene. The polymer becomessoft at 145150 C. and can be pressed between heated metal plates intoclear sheets having extremely good mechanical properties.

EXAMPLE 10 Example 9 is repeated but 2 grams of uranium tetrachlorideare used instead of the thorium compound. A polyethylene which hasexcellent properties is produced.

EXAMPLE 1 1 products.

EXAMPLE 12 2 grams chromium acetyl-acetonate are added to 20 cc.aluminum triethyl with exclusion of air. Under heat the solution turnsblack, but there is no appreciable precipitation. The mixture is thendiluted with 200 cc. hexane in a 500 cc. autoclave, whereupon a pressureof 70 atmospheres is produced with ethylene and the autoclave is shaken.The pressure drops rapidly to about 25 atmospheres because the solventfirst absorbs the ethylene to saturation. More ethylene is added and themixture shaken. The pressure now drops somewhat more slowly. Thisoperation is repeated several times at increasingly long intervals. Inthe course of 24- hours 110 grams ethylene were introduced into theautoclave. The pressure at the end of the 24 hours was still 40atmospheres. The temperature rose preciptately to 30 C. at the beginningof the experiment. After 24 hours 41 grams of unchanged ethylene wereblown ofi', whereupon the autoclave was opened and the contents wereimmediately mixed with methyl alcohol. The contents of the autoclave nowform a semisolid mass which is washed out, sucked off and subsequentlyheated with methyl-alcoholic hydrochloric acid in order to remove thecatalyst components, and again filtered. After drying, 69 grams of acolorless powder insoluble in all organic solvents were obtained whichcould easily be pressed into sheets between heated metal plates.

EXAMPLE 13 2.5 grams of tungsten hexachloride WCl are added to 20' cc.aluminum triethyl and the mixture ground in 200 cc. hexane in a ballmill for 2 hours. The catalyst suspension is then introduced into a 500cc. autoclave. Thereupon ethylene with a pressure of atmospheres isallowed to act on the mixture at 100 C. for 24 hours. When the autoclaveis opened about 10 grams of polyethylene products will be found.

1 5 EXAMPLE 14 Add to 20 cc. aluminum triethyl 0.2 grams molybdenumacetyl-acetonate. Then proceed as in Example 13 and after 24 hours at100 C. and 85 atmospheres ethylene pressure about 5 grams polyethyleneof the type described will be obtained.

EXAMPLE 15 To cc. aluminum triethyl add 0.2 grams tantalum pentachlorideTaCl and treat the mixture in the manner described in connection withExamples 13 and 14. At 90 C. and 90 atmospheres ethylene pressure 6 to 8grams polyethylene are obtained after 20 hours.

EXAMPLE 16 Add 4 grams zirconium tetrabromide to 20 cc. aluminumtriethyl, grind the mixture for 3 hours in 200 cc. hexane in a ball milland introduce the suspension into a 500 cc. autoclave. At 60 to 70 C.and 70 atmospheres ethylene pressure, 122 grams polyethylene areobtained after 24 hours.

EXAMPLE 17 Introduce a mixture of cc. aluminum triethyl and 0.5 grams KTiF into 200 cc. hexane in a ball mill. Grind for 3 hours. Bring themixture into a 500 cc. autoclave as indicated in Example 16. After 10hours reaction at 100 C. and 60 to 70 atmospheres ethylene pressure 45grams of polyethylene are obtained.

EXAMPLE 18 Titanium hydrated oxide produced by careful hydrolysis of 5grams titanium tetrachloride at 0 to 10 C., after being filtered andwashed with ice water is shaken three times with 100 cc. acetone, oncewith 100 cc. ether and three times with petroleum ether, at 0 C. andcompletely dried after being subjected to suction for 1 hour. 0.4 gramsof the titanium compound thus treated are suspended in 100 cc. hexaneand mixed with 20 cc. aluminum triethyl introduced drop by drop at 0 C.under nitrogen. The suspension is then introduced into a ball mill undernitrogen and ground for 3 hours. The suspension is then filled into a500 cc. autoclave under nitrogen. Under the conditions indicated inExample 17, grams of polyethylene are obtained.

EXAMPLE 19 The zirconium, precipitated as hydrated oxide from an aqueoussolution of zirconium nitrate by adding ammonia drop by drop at 0 C., isfiltered, washed and dried as described in Example 18. 3 grams ofzirconium hydrated oxide dried in the manner above indicated are addedto 50 cc. aluminum trioctyl and this mixture is ground in 200 cc. hexanein a ball mill for 2 to 3 hours. Under the conditions indicated inExample 18, 55 grams polyethylene are obtained with the aid of acatalyst.

EXAMPLE 20 250 millimols aluminum triisobutyl are dissolved in 250 cc.diesel oil and 25 millimols zirconium tetrabutylate added. Stirringintensively, the mixture is heated for 5 hours at 100 C. The catalystmixture is diluted with 1500 cc. diesel 'oil and ethylene introduced at550 C. for 6 hours. 10 grams polyethylene are formed.

EXAMPLE 21 50 cc. of a 0.5 molecular solution of aluminum triisobutyl indiesel oil are dissolved in 100 cc. diesel oil and 50 cc. of a 0.5molecular solution of titanium tetrachloride in diesel oil added drop bydrop. The mixture is then stirred for 10 minutes at room temperature,diluted with 2.3 liters of diesel oil and ethylene introduced at 60 C.After 1 hour polymerization at 60 to 70 C., 230

grams of polyethylene are obtained.

- 16 EXAMPLE 22 2.1 grams of titanium tetrachloride (1.2 cc.)=11.4millimols were added to a suspension of 11.7 gin-of aluminumtriphenyl=45.6 millimols in 500 cc. of Aliphatin. The white aluminumtriphenyl suspension turned brown immediately on the addition oftitanium tetrachloride. After shaking overnight in an oscillating ballmill only approximately 15% of the chlorine bound to titanium was stillto be found in the centrifuged. solution.

The whole suspension was boiled with 500 cc. of-Aliphatin and introducedinto a 5-liter stirring autoclave. Ethylene was pumped in to a pressureof 20 atmospheres and the autoclave was slowly heated.'During heating upthe pressure rose slowly and thereafter fell'between 30 and 40 C. to 16atmospheres. The pressure was again restored to 20 atmosphere by oncemore pumping in ethylene and then fell only slowly in the course of .aday to 13 atmospheres. After blowing ofi unreacted ethylene, theautoclave was opened. The reaction mixture was black and pasty. Afterseparating the Aliphatin by'sectional filtration, boiling withmethanolic hydrochloric acid and filtering with suction drying, mg. of agray polyethylene were obtained. A total of approximately 150'gm. ofethylene had been introduced.

Zirconium tetrachloride, zirconnium-IV-acetylacetonate, thoriumacetylacetonate, uranium hexachloride or chromium-III-acetylacetonate,using molar equivalent amounts under otherwise the same reactionconditions, can be employed instead of titanium tetrachloride to obtaina high molecular polyethylene. Similarly Al-tritolyl, Altrixylyl andAl-trinaphthyl, using molar equivalent amounts under otherwise the samereaction conditions, when substituted in this example for the tri-phenylaluminum compound will give similar results in combination with any ofthe heavy metal compounds herein specified.

EXAMPLE 23 A suspension of 7 gm. of sodium phenyl in 100 cc. of benzolwas mixed with 5 gm. of diethyl aluminum chloride introduced drop bydrop with vigorous stirring. After a period of reaction of 1 hour, thesediment was centrifuged otf and the benzol solution freed from benzolby evaporation in a vacuum. The residue contained no chlorine and itsanalysis showed a compound having the formula 4 gm. of the phenylaluminum diethyl thus produced were ground in an oscillating ball millfor 2 hours with 4 gm. of zirconium chloride and 200 cc. of hexane,whereupon the brownish black suspension was introduced into a 500 cc.autoclave and 75 gm. of ethylene were pumped in. The autoclave Was thenshaken for 35 hours at a temperature of to C. During this period thepressure had fallen to 30 atmospheres. After cooling, 10 gm. of ethylenewere blown olf. The autoclave contained 62 gm. of asbestos-likepolyethylene. For purification purposes, the polyethylene was separatedby filtration from the solvent and boiled with methanolic hydrochloricacid, which dissolved the catalyst residue contained in thepolyethylene. The product was thereafter washed with methanol andacetone to remove any hydrochloric acid still adhering. In this Way asubstantially purewhite product was obtained.

EXAMPLE 24 About 4.75 gms. of titanium tetrachloride are introduced intoa solution of 5.7 gms. triethyl aluminum in 250 cc. of a Fischer-Tropschdiesel oil (suitably' freed, by hydrogenation, of unsaturatedconstituents and successively distilled over sodium) with stirring andunder a nitrogen atmosphere. Agitation is continued for one hour at roomtemperature. A suspension of a brown-black substance in the diesel oilis formed. The suspension of the catalyst thus obtained is introduced,with stirring into a liter autoclave filled with nitrogen and containing1.0 liter of the diesel oil, and 600 gms. of dried, air-free propyleneare pumped in. The temperature is raised to 70 C., stirring beingcontinued, whereupon the pressure increases to a maximum of 21 atm.Within 72 hours, the pressure decreases to 11.0 atm. The unreactedpropylene is then released from the warm autoclave and 225 gms.propylene are recovered. The solid polypropylene occurs in a paste-likesuspension in the diesel oil. The suspension is somewhat dark in colordue to the presence of portions of the catalyst therein. The solvent isremoved from the polypropylene by suction, and the polymer is then freedof diesel oil by washing with acetone. The polymer isthen decolorized byheating it under stirring, with methanolic hydrochloric acid. Thecolorless polypropylene is washed under suction with water to remove thehydrochloric acid, then with acetone to remove the bulk of the moisture,and finally dried.

An additional quantity of the polypropylene is recovered from the dieseloil mother liquor by precipitation with acetone, and may be processed asdescribed. A total yield of 338 gms. of granular polypropylene isobtained.

The solid, granular polypropylene may be pressed at 140 C. to obtainflexible sheets or films which appear transparent in thin films andopaque in thick layers.

EXAMPLE 25 EXAMPLE 26 Example 24 is repeated, except that in addition topropylene an ethylene partial pressure of 1-3 atm. is maintained in theautoclave by connecting the latter with an ethylene cylinder and bycarefully adjusting the valve. Because ethylene polymerizes more rapidlythan propylene, the composition of the liquid phase is appropriatelycontrolled by taking small samples and by gas analysis; to maintain anamount of ethylene in the liquid which is only a few percent (up to ofthe propylene. A solid copolymer is obtained. It may be formed intofoils having properties between those of film-forming polyethylene andpolypropylene.

EXAMPLE 27 About 30 cc. of air-free Fischer-Tropsch diesel oil distilledover sodium and completely saturated by hydrogenation are introducedinto a small (150 ml.) ball mill arranged for working under ntirogen,together with 17.1 gm. triethyl aluminum and 11.7 g. zirconiumtetrachloride, and the whole is ground for 24 hours to obtain anintimate mixture. A thick black suspension is obtained. It is mixed with1.0 liter of the same diesel oil and introduced under nitrogen into a 5liter autoclave equipped with a stirrer. 590 g. of propylene are thenpumped in at room temperature, stirring is commenced, and the autoclaveis heated to 80 C. Within 50 hours the pressure falls from the initial23 atm. down to 14.2 atm. The reaction is interrupted, the autoclave isallowed to cool, and the excess propylene is vented. 190 g. of propyleneare recovered. The mass contained in the autoclave is'a thick blackslurry which, after the addition of acetone and filtration undersuction, becomes colorless. The residual catalyst is extracted byheating with alcoholic hydrogen chloride. After repeated washing withacetone and drying, 400 g. of a white, fiocculent polypropylene areobtained. The polymer can be easily pressed into foils and rolled into asheet.

EXAMPLE 28 The catalyst is prepared from 17 .1 g. triethyl aluminum and4.75 g. titanium tetrachloride in 250 cc. diesel oil,

and introduced, together with 1390 g. isobutylene, into a 5-literautoclave filled with nitrogen and provided with a stirrer. Theautoclave is then heated to 40 C. and the pressure, initially 5 atm., israised an additional 4 atm. by pumping in ethylene. The absorption ofethylene com mences at once with spontaneous increase of the temperatureto 55 C. An ethylene partial pressure of 4 atm. is maintained. After atotal of 6 hours, g. ethylene are absorbed. The valve of the ethylenecylinder is then closed, and stirring is continued until the pressuredrops to only 5 atm. After cooling, the excess isobutylene is released.The mass remaining in the autoclave is a black slurry. It is dilutedwith acetone, filtered under suction, thoroughly washed, and furtherworked up. 216 g. of the copolymer of isobutylene and ethylene areobtained, about 60 g. of the isobutylene being copolymerized asevidenced by the infra-red spectrum of the copolymer, which is verydifferent from the spectrum of ethylene homopolymers.

EXAMPLE 29 4 g. of aluminum triethyl were dissolved under nitrogen in240 cc. of dry Fischer-Tropsch diesel oil and 2.8 g. of titaniumtetrabutylate dropwise added thereto. After stirring for 10 minutes atroom temperature the mixture was introduced into a 5 liter low pressurestirring autoclave together with 750 cc. of dry Fischer-Tropsch dieseloil. After heating the autoclave to a temperature of 6070 C., ethylenewas pumped in up to a pressure of 15 atmospheres and temperature andpressure kept constant for five hours. The reaction was thendiscontinued, the autoclave cooled and the excess ethylene blown off.From a total of 154 g. of ethylene there were thus obtained 78 g. of aplastic-like polymer with an average molecular weight of about 690,000(viscosity (1,): 14.7).

EXAMPLE 30 4 g. of aluminum triethyl were dissolved in 240 cc. of dryFischer-Tropsch diesel oil under nitrogen and 5.6 g. of .titaniumtetrabutylate dropwise added thereto. This mixture was then treatedaccording to the process of Example 29. After five hours ofpolymerization there were obtained 52 g. of a plastic-like polyethylenewith an average molecular weight of about 550,000 (viscosity (1 12.2).

The products in accordance with the invention are characterized by theirinherent low melt index. The melt index, as is well understood in theart, expresses the characterization of a moldable product to berelatively stable with respect to its viscosity with a relatively widetemperature range. In other words the viscosity-temperature curveisrelatively flat or less steep so that a desired degree of viscosity canbe retained over a greater temperature range without the danger of a toogreat. fluidity causing a quote running away conditions.

Polyolefines and especially polyethylene prepared in accordance with theinvention possess for molecular weights of a magnitude of about 50 to60,000, a melt index not in excess of substantially of about 1. Withincreasing molecular weights the melt index of the products inaccordance with the invention are even lower being, for instance, of avalue of approximately less than 0.1 for molecular weights of anmagnitude of approximately 100,000 to 120,000.

By way of further exemplification of the benefits obtainable byselection of mol ratios within the sensitive range of a given catalystcombination, useful in accordance with the invention, the examples setforth in the following Tables 11 to VII (FIGS. 2-6) are furnished:

Table II shows the results of experiments obtained when using analuminum tridecyl and titanium tetrachloride system. In this case, thesteep range of the molecular ratio between aluminum tridecyl andtitanium tetrachloride is between 0.5 :1 and 2:1. These results are alsoillustrated by curve B in FIG. 2 of the accompanying drawings.

ee -em T'Ai L .1"

' .llrlolecillar Yield atc'er' average ratio, I 1 5,0'miuutes Imolecular Number of Al(CmHn)a: Colour of reaction,g. (n) Weight of Iexperiment -TiCl catalyst polyethylenedl./g. thepolymer' 193 7.68 1810,000" 20a 8.12 .330, 000 213 7. 45 298,000 177 4. 75 170,000- 2501.03 26,000 brown. M a H Table III shows the ratios in an aluminumtriisobutyl ratio range. This is' wll" illustrated" curve "and titaniumtetrachloride system. In this case, the molecular weight of the polymercan be closely influenced by regulating the molecular ratio of aluminumtriisobutyl to titanium tetrachloride between 05:1 and 3:1. The resultsof this experiment are particularly pronounced, since in the case themolecular weight can be regulated between about 50,000 and about1,090,000. FIG. 3 of the 4 which is plotted on the values rjrablef v anthe steep portion C and 'th'e-Qless steeply I section e. Thus, when'theprimary :cbnsiderat n i selection of a specfiicmolecular weight which1511635011- ably accurately reproduceable,' curve section je will rmit agreater latitude of error or deviation inlrn'ol r without appreciablyinfecting, the desireci, molecuar accompanying drawings shows theextraordlnarily steep weight.

TABLE IV. I

' 1 Average" Molecular Yield after H molecular. ratio, 1 hr. reactionweight Numberoi A1(CaH7)aI Colour of g. poly: 1) 'ofth'e experirnentT1014 catalyst 'ethyleue dl./g. polymerv 0.4 Brown. 432 1.75 50,000 0.190.5 do 502. 2.12... 63,000. 0.31 0.7 (10 415 3.0 95,000 0.03 1 Brownlsh-.321, 7.67 310,000 0.005

black. 2 Blackish- 290 9.40, 395,000 o.005

brown.

portion C of the curve C in the sensitive range portion between 0.5 :1and 3:1.

Table V shows the "results of eXperi'r'nents obtained when using analuminum triethyl titanium chloride sys- TABLE III Yield after AverageMolecular 50 minutes molecular ratio, reaction, weight Number of Al(-C4Ho)a: Colour of g. polyethyl- (1; of the Melt experiment TiClicatalyst ene dl./g. polymer index 0 5 Black 281 1. 97 50,000 0 .do 3034. 15 145,000 0. do 211 6. 4 250,000 1 .do... 230 7. 300,000 1 5 do 28011. 56 510, 000

2 do 281 13. 3 600,000 2 ...-d0 316 13. 57 620,000 3 do 152 21. 25 1,090,000 4 do 195 20. 2 1, 030, 000 6 do 110 19. 2 900,000 d0 20.21,030,000

As will be seen from Table III and FIG. 3 molecular weights of anespecially high order of magnitude are obtained when using branchedalkyl radicals attached to the aluminum.

Table IV illustrates the results of experiments obtained when using analuminum propyl and titanium tetrachloride system. As shown in thistable the steep range of the molecular weight/mol ratio values liesbetween mol ratios of 04:1 and 1:1. In this case the entire sensitiverange extends to in excess of 6:1. When costs of material are notnecessarily a critical impediment TABLE v Molecular Yield afterl Average1 r hour reaction, moleculan Number of Al(C2H5)3: Colour of g.polyethyl- (1 weight of the Melt experiment TiCh catalyst 'en'e .lg.polymer= index .4 Brown 310 1.41 38,000 2 0.5 0.; 308 1.92 55,000 0.550.8 Dark-brown-... I 311 2. 80. 90,000 0.05 1 0 327' 5.82 220,000 0.0052 Brownish-black- 340 6.35 245,000 01 005 3 d0 353 6. 72 260,000 0..0 057 Black 7.70 310,000 0. 005

it is,in same cases desirable to operate within a less Table VI shows afew limiting experiments (steep steeply increasing molecular weightportion of the mol 75 portion) for additional organic aluminum compoundsand heavy metaicompounds. With the experiments using 22 by mixing atleast one aluminum trialkyl with a heavy metal compound selected fromthe group consisting of the salts, other than pure alcoholates, and thefreshly precipitated oxides and hydroxides of metals of Groups IV-B, V-Band VI-B of the Periodic System, including thorium and uranium, andrecovering the high molecular "in FIG. 6. polyethylene formed.

TABLE VI Reac- Average Molection Yield, g. molecular Numbero! uJarColour time, of poly- 1) weight 0! Graph experiment ratio catalyst hrethylene dL/g. polymer F 1 12 Reddish' 4 30 14.9 700,000

0 2 150 3.0 05,000 7 2 10 2.9 90,000 a 2 9 3.1 100,000 9 7 12 o. 2 5 7.0,000 10 14 do 2 4 8.3 ,000

1 Al(C2Hr)s; zirconiumaeetylacetonate.

e AI(C2H5):I chromiumacetylacetonate.

Table VII shows the results of experiments when using 2. Methodaccording to cl i 1 in hi h said conan aluminum triphenyl-titaniumchloride system. The tacting is effected at a pressure below 10atmospheres. steep range of molecular weight in relation to mol ratio 3.Method according to claim 1 in which said conextends in this casebetween 0.5 :1 and 1:1. In this case tacting is effected atsubstantially atmospheric pressure. the steep section C is followed aspart of the sensi- 4. Method according to claim 1 in which said contiverange by a more gradually inclining curve section tacting is eifected ata temperature above 50 C.

e which permits the obtaining of a specific molecular 5. Methodaccording to claim 1 in which said conweight in the range from about370,000 to about 560,000. tacting is efifected in the presence of asolvent for said TABLE aluminum trialkyl and said heavy metal compound.

1 Yi m it A 6. Method according to claim 1 1n which said con- 13,: g223; tacting is effected in the presence of an excess of alu- Numher oiAl(CaH s)a: tion, g. 1(11) h weight of u tnalk L expenment T101polyethylene d t epo 7. Method according to claim 1 in which saidcatalyst 0-? -g 18.388 is formed by mixing 2n-3n mols of aluminumtrialkyl 2 g 5601000 per mol of said heavy metal compound, nrepresenting 4 4 the valency of said group member. 8. Method for thepolymerization of ethylene, which when VaTYmg 11101 ratios of yoffhealummum alkyl comprises contacting ethylene with a catalyst formedY Y metal PQ P comblnatlens, repl'esemed by mixing, in the presence of asolvent, an aluminum triy the examples e and P P each case alkyl with aheavy metal compound while at least one a sllfiielent numbel: offllfierfmt Fi runs under thereof is in solution in said solvent, andrecovering the otherwise substantially identical conditions, curves orhigh molecular Polyethylene formed, said heavy metal P may be P t thesel e Values shown? compound being selected from the group consisting ofthe SeIlSltlVe ranges 81311131 to those ldentlfied salts, and thefreshly precipitated oxides and hydroxides of metals of Groups IV-B, V-Band VI-B of the Periodic The eifectvve or most effective utilization ofthe sens1- System including thorium and uranium. tive range of variouscatalyst combinations applicable in Method according to claim 8 in whichsaid accordance With the mvem10l1 e f 111 most cases tacting is eifectedat a pressure below about 100 atmossrrable to use a relatively pureinitial monomer. As above pheres and at a temperature above about Qpointed out, if for instance ethylene contains certain im- 0 Methodaccording to claim 8 in which said purities, these mayinactivateportions of the heavy metal aluminum trialkyl is aluminumtri(isohutyl) comPound, P the alummum Y P 11. Method according to claim10 in which said heavy ent in the solution and may thus undesirablyshift the meta1compouhdisahahde ratio imtlany Pf between the catalyft f12. Method according to claim 11 in which said halide nents. Thesedifficulties, however, may be avoided if the is a ch1oride e y e the gmlxture COIItPmmg hy 18 13. Method according to claim 11 in which saidconllmlnal'lly contacted Wlth olganlc metal tacting is eifected at apressure below about 100 atmos- Pollllds, P e y orgafllc eompwfldspheres and at a temperature above about 50 C.

fore entering the reaction vessel in which it is to be 14 Methodaccording to claim 13 in which said 1 contacted with the hereindescribed catalyst material. ride isatitanium ch1oride When pfoeeefilng111 thls e i Polymenzanon of 15. Method according to claim. 14 in whichsaid chlothe ethylene is actually carried out in two separate steps. idis i i tetrach10ride The organic metal compound useable in the firststep 16. Method according to claim 8 in which said heavy of the justdescribed two-step procedure is preferably one metal compound is anoxychloride. corresponding to the general formula RAlXY or RMeY A 17.Method according to claim 8 in which said heavy in which R is hydrogenor a hydrocarbon radical, X is metal compound is an acetylacetonate.

R or OR, Y is R or 0R, R is a hydrocarbon radical 18. Method accordingto claim 17 in which said and Me is a bivalent metal, preferablymagnesium or acetonate is zirconium acetyl acetonate. zinc. 19. Methodaccording to claim 8 in which said alu- What is claimed is: minumtrialkyl averages in composition about C to C 1. Method for thepolymerization of ethylene, which per alkyl group, and in which saidheavy metal compound comprises contacting ethylene with a catalystformed is a chloride and in which said contacting is effected at tw e r129.119;9591 9 1- if t l eri in te hrlene whi h co pr se m a s' s o t ena-pr ss eiast qssfibsv 1'0; and about 100 atmospheres at an elevatedtemperature "between about 50 C.- and about, 250 C with a catalystformed by mixing titanium tetrachloridewith a substantial molarproportion of an aluminum trialkyl, sufficient to reduce the valencestate of the titanium, at least in part, and recovering high molecularweight solid polyethylene from the resulting mixture.

21. Method for polymerizing ethylene which comprises contacting gaseousethylene with a catalyst consisting essentially of the reaction productof titanium tetrachloride and aluminum trialkyl, and recovering highmolecular weight solid polyethylene from the resulting mixture.

22. Method for the polymerization of alpha-olefins, which comprisescontacting such olefin with a catalyst formed from an organometalcomponent comprising an aluminum trialkyl and a heavy metal componentcomprising a compound selected from the group consisting of salts andthe freshly precipitated oxides and hydroxides of metals from GroupslV-B, V-B and VI-B of the Periodic System, including thorium anduranium, and recovering a high-molecular polymer formed.

23. Method according to claim 22, in which said heavy metal component isa titanium chloride.

24. Method according to claim 23, in which said organometal component isaluminum triethyl.

25. Method according to claim 22, in which said organometal component isaluminum triethyl.

26. Method according to claim 22, in which said ole fin is propylene.

is propylene.

o ulyst is formed-by mixing in which said 9. 91s I I in which; saidcatasai i -sansmstal ce p e and said heavy metal component in thepresence of an organic solvent. A,

30. Method according "touclaim. 29, in which saidiheavy metalcomponentfis a titanium chloride,

31.,. Method jaccording to,claim 30, in which said olefin 32. Methodawardin to,.,.claim' '31, in which said organometal component isaluminum triethyl.

References Cited UNITED srATBs PATENTS 3,1 14,743

12/1963 Horne, Jr; 260-94.3 2,959,576 11/1960 Payne 26094.9 (3 2,200,4295/1940 eri-in et a1: 26088.2 6 2,691,647 10/1954 Fieldfetifala, 26o+ss.2R 3,257,332 6/1966 Zieglene'talz 260--94.9B 3,574,138 4/1971-Zieg-l'en-et al '260-94.9 B

JOSEPH L. SCHOFER, iir ifiia iaxamineffl Q A. HOLLER, Assistan tEx'aminer us. CIJ'XR, 260-882 R, 93.7,9484 Y e UNITED STATES PATENTOFFICE Q CERTIFICATE @F CORRECTION Patent No. 3,826,792 Dated uly 301974 Inventor(s) Karl Ziegler, Heinz Breil, Erhard Holzkamp and HeinzMartin It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

r- -1 C01. 2 line 50, after "as" second occurrence, insert -wel1 Col.2', line 51, after "such", second occurrence, insert -as Col. 2, line55, change "connot" to --connote-' Col. 3, line 60, change "comple"; to-compl'ex-- Col. 7, line 43, change "section e" to -section c-- Col. 8Table I last column, bottom line, insert 4-- Co1.12, line 5', change'browen" to broken-- Col.l4, line 54, change "preciptately" to'precipitately e C01. 15, line 63, change "550" to *5S-- C01. 20, Table'IV, last column, bottom line, change 0. 00"

' to 0. OO5 1 Signed and sealed this 22nd day of October 1974.

- (SEAL) Attest: I

McCOY M. GIBSON JR. 0., MARSHALL DANN l Attesting Officer 7 Qommissionerof Patents

